Detection of chemical explosives using multiple photon signatures.

A template-matching procedure is being investigated for rapid detection of improvised explosive devices at standoff distances. Photon-scattered and photon-induced positron annihilation radiation responses are being studied as a part of a signature-based radiation scanning approach. Back-streaming radiation responses, called signatures, are compared to templates, which are collections of the same signatures if the interrogated volume contained a significant amount of explosive. Experiments have been conducted that show that explosive surrogates (fertilizers) can be distinguished from several inert materials.